Photoluminescence properties of M₂Eu_xLn_1-xAlO₅(M=Ca, Sr, Ba, Ln=La, Gd, Lu) red phosphor

The red emitting phosphors M₂Eu_xLn_1-xAlO₅ (M=Ca, Sr, Ba, Ln=La, Lu, Gd) were synthesized through the solid state reaction technique. The photoluminescence properties were described. Upon excitation with UV and near UV light excitation, the photoluminescence emission spectra could be assigned to the transitions of Eu³⁺ from the initial state ⁵D₀ to the final states ⁷F_J (J=0,1,2,3,4). The two strong emissions peaked at 590 nm and 620 nm, which arose from the ⁵D₀-⁷F₁ and ⁵D₀-⁷F₂ transitions of Eu³⁺, respectively. The photoluminescence excitation spectra show abroad O^2--Eu³⁺ charge-transfer band and f-f transitions. O^2--Eu³⁺ charge-transfer bands of M₂Eu_xLa_1-xAlO₅ (M= Ca,Sr,Ba) shift to the longer wavelength in order of Ca, Sr, Ba. The replacement of Ln in Sr₂Eu_xLn_1-xAlO₅ by La, Gd and Lu was studied. The dependence of the integrated luminescence intensities on Eu³⁺ concentration was presented. The lifetimes of Sr₂Eu_xLa_1-x-AlO₅ and Sr₂Eu_xGd_1-xAlO₅ were analyzed.